The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
R H Lenssen - One of the best experts on this subject based on the ideXlab platform.
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series hybrid electric aircraft comparing the well to Propeller efficiency with a Conventional Propeller aircraft
2016Co-Authors: R H LenssenAbstract:THE aviation industry is responsible for 12% of the total transportation impact of CO2 while awareness, for decreasing the total carbon footprint, is rising. Both the aerospace and the automotive industry are facing an increasing pressure from society to make the transportation sector more sustainable. Within the automotive industry slowly an increase in electric vehicles can be noticed (<1%). Also in the aerospace industry a rise in electrification can be seen, with small aircraft as the E-Star and E-Fan (two seaters) as commercial examples. Electrification of the transportation sector could further result in a decrease in noise and an increase in lifespan of parts as vibrations are decreased. This master’s thesis is written in conjunction with the chair Flight Performance and Propulsion at the faculty of Aerospace Engineering at the Delft University of Technology. The main purpose is to gain more insight in modelling an (hybrid) electric aircraft and the potential improvements with respect to well-to-Propeller efficiency (usefull energy over total energy ratio). This is achieved by first creating a baseline Conventional Propeller aircraftmodel (ATR72) and then a hybrid electric version of the same aircraft. The variations between the sub-models and validation data are calculated in order to have a feeling for the accuracy of each individual model. Furthermore, both the theoretical and current practical state of technologies are used in the overall model. Finally, a sensitivity analysis is performed to find the driving parameters in the outcome of the model. The analysis of the series hybrid electric aircraft showed first of all that the expected advantages of the concept are ’small to non-existent’. The electric energy used to charge the batteries should first of all come from a renewable source of energy to make the concept feasible. Secondly, the theoretical limits of technology should be approached in order for the well-to-Propeller efficiency to exceed that of the Conventional ATR72 aircraft (with a maximum of 2%). It is seen that the model converges to an all electric version of the ATR72 if the battery energy density is increased to 2,802 [Wh/kg], this would correspond to the theoretical limit of Lithium Sulphur battery-technology. Furthermore, for an increase in voltage the battery efficiency decreases while all other components will improve in efficiency. The optimum is found in increasing the voltage up to the practical limit of 25 [kV]. Electric propulsion creates new design possibilities as distributed propulsion and variable shaft-speed. Within this thesis it is however shown that the ’benefits’ of distributed propulsion do not outweigh the downsides (increase inweight and decrease in efficiency of all components). Furthermore electric motors allow for temporary torque overloading, by decreasing the rotational speed and increasing the torque, the overall result is an increase in efficiency, which could for example be usefull during the climb or take-off phase. Concluding, the concept of series hybrid electric aircraft is at this moment in time rendered infeasible. The potential within a 35 year time-frame is doubtfull as especially battery technology should improvewith at least 400 [%]. In order to accelerate the transition to hybrid electric or all electric aircraft, the main areas of research should be: battery technology and the integration of alternating current and superconducting materials in rotating machine parts.
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Series Hybrid Electric Aircraft: Comparing the Well-to-Propeller Efficiency With a Conventional Propeller Aircraft
2016Co-Authors: R H LenssenAbstract:THE aviation industry is responsible for 12% of the total transportation impact of CO2 while awareness, for decreasing the total carbon footprint, is rising. Both the aerospace and the automotive industry are facing an increasing pressure from society to make the transportation sector more sustainable. Within the automotive industry slowly an increase in electric vehicles can be noticed (
Alexandre Capitao Patrao - One of the best experts on this subject based on the ideXlab platform.
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Wake Analysis of an Aerodynamically Optimized Boxprop High Speed Propeller
Journal of Turbomachinery, 2019Co-Authors: Alexandre Capitao Patrao, Anders Lundbladh, Tomas Grönstedt, Gonzalo Montero VillarAbstract:The Boxprop is a novel, double-bladed, tip-joined Propeller for high-speed flight. The concept draws inspiration from the box wing concept and could potentially decrease tip vortex strength compared with Conventional Propeller blades. Early Boxprop designs experienced significant amounts of blade interference. By performing a wake analysis and quantifying the various losses of the flow, it could be seen that these Boxprop designs produced 45% more swirl than a Conventional reference blade. The reason for this was the proximity of the Boxprop blade halves to each other, which prevented the Boxprop from achieving the required aerodynamic loading on the outer parts of the blade. This paper presents an aerodynamic optimization of a 6-bladed Boxprop aiming at maximizing efficiency and thrust at cruise. A geometric parametrization has been adopted which decreases interference by allowing the blade halves to be swept in opposite directions. Compared with an earlier equal-thrust Boxprop design, the optimized design features a 7% percentage point increase in Propeller efficiency and a lower amount of swirl and entropy generation. A vortex-like structure has also appeared downstream of the optimized Boxprop, but with two key differences relative to Conventional Propellers. (1) Its formation differs from a traditional tip vortex and (2) it is 46% weaker than the tip vortex of an optimized 12-bladed Conventional Propeller.
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On the Aerodynamic Design of the Boxprop
2018Co-Authors: Alexandre Capitao PatraoAbstract:Economic factors and environmental awareness are driving the evolution of aircraft engines towards increasingly lower fuel consumption and emissions. The Counter-Rotating Open Rotor (CROR) is actively being researched around the world, promising a significantly increased propulsion efficiency relative to existing turbofans by employing two, unducted, counter-rotating Propeller blade rows, thereby increasing the bypass ratio of the engine and decreasing nacelle drag. Historically, these engines have been plagued by high noise levels, mainly due to the impingement of the front rotor tip vortices on the rear rotor. In modern designs, the noise levels have been decreased by clipping the rear, counter-rotating Propeller. This comes at a cost of decreased efficiency. An alternative, potential solution lies with the Boxprop, which was invented by Richard Avellan and Anders Lundbladh. The Boxprop consists of blade pairs joined at the tip, and is conceptually similar to a box wing. This type of Propeller could weaken or eliminate the tip vortex found in Conventional blades, thereby reducing the acoustic signature. This thesis summarizes advances done in the research regarding the aerodynamics of the Boxprop. Aerodynamic optimization of the Boxprop has shown that it features higher Propeller efficiency than Conventional Propellers with the same number of blades, but lower Propeller efficiency than Conventional Propellers with twice as many blades. A key design feature of optimal Boxprop designs is the sweeping of the blade halves in opposite directions. This reduces the interference between the blades and allows the Boxprop to achieve aerodynamic loading where it is most efficient - close to the tip. A Wake Analysis Method (WAM) is presented in this work which provides a detailed breakdown and quantification of the aerodynamic losses in the flow. It also has the ability to distinguish and quantify the kinetic energy of the tip vortices and wakes. The Wake Analysis Method has been used to analyse both Boxprop blades and Conventional Propeller blades, and insights from it led to a geometric parametrization and an optimization effort which increased the Boxprop Propeller efficiency by 7 percentage points. Early Boxprop blades did not feature a tip vortex since aerodynamic loading near the tip was relatively low. The optimized Boxprop blades have increased the aerodynamic loading near the tip and this has resulted in a vortex-like structure downstream of the Boxprop at cruise conditions. This vortex is significantly weaker and of different origin than the tip vortex of a Conventional Propeller. A CROR featuring the Boxprop as its front rotor (BPOR) has been designed and its performance at cruise is competitive with other published CRORs, paving the way for future work regarding take-off performance and acoustics.
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Aerodynamic and aeroacoustic comparison of optimized high-speed Propeller blades
2018 Joint Propulsion Conference, 2018Co-Authors: Alexandre Capitao Patrao, Daniel Lindblad, Anders Lundbladh, Tomas GrönstedtAbstract:The Boxprop is a high-speed Propeller concept intended for aircraft engines, which features blade pairs connected at the tip in order to decrease tip vortex strength, possibly reducing noise and improving aerodynamic performance relative to Conventional high-speed Propellers. This paper investigates the aerodynamic and aeroacoustic performance of three aerodynamically optimized high speed Propellers; a 6-bladed Conventional Propeller, a 12-bladed Conventional Propeller, and a 6-bladed Boxprop. Performance results will be be compared for the three designs, with a focus on sectional performance and wake flow characteristics, and will show that the 6-bladed Boxprop performance lies somewhat in-between its 6 and 12-bladed Conventional counterparts. The noise level at various observer positions is presented, and shows that the noise roughly follows the values of efficiency for the three Propellers, with the Boxprop noise level being higher than the 12-bladed Conventional Propeller, but lower than the 6-bladed one. The lower blade loading and higher efficiency of the Boxprop relative to the 6-bladed Conventional Propeller results in slightly lower levels of noise at cruise.
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wake and loss analysis for a double bladed swept Propeller
Proceedings of ASME Turbo Expo 2016: Turbine Technical Conference and Exposition Seoul South Korea Jun 13-17 2016, 2016Co-Authors: Alexandre Capitao Patrao, Anders Lundbladh, Richard Avellan, Tomas GrönstedtAbstract:Inspired by Prandtl’s theory on aircraft wings with minimum induced drag, the authors introduced a double-bladed Propeller, the Boxprop, intended for high-speed flight. The basic idea is to join the Propeller blades pair-wise at the tip to improve aerodynamics and mechanical properties compared to the Conventional Propeller. The rather complex geometry of the double blades gives rise to new questions, particularly regarding the aerodynamics. This paper presents a Propeller wake energy analysis method which gives a better understanding of the potential performance benefits of the Boxprop and a means to improve its design. CFD analysis of a five bladed Boxprop demonstrated its ability to generate typical levels of cruise thrust at a flight speed of Mach 0.75. The present work shows that the near tip velocity variations in the wake are weaker for this Propeller than a Conventional one, which is an indication that a counter rotating Propeller designed with a Boxprop employed at the front may exhibit lower interaction noise.
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Simulation and Analysis of a Novel Open Rotor Propeller - the Boxprop
2016Co-Authors: Alexandre Capitao PatraoAbstract:Economic factors and environmental awareness is driving the evolution of aircraft engines towards increasingly higher efficiencies, reaching for lower fuel consumption and lower emissions. The Counter-Rotating Open Rotor (CROR) is actively being researched around the world, promising a significantly increased propulsion efficiency relative to existing turbofans by employing two, counter-rotating Propeller blade rows, thereby increasing the bypass ratio of the engine. Historically, these engines have been plagued by very high noise levels, mainly due to the impingement of the front rotor tip vortices on the rear rotor. In modern designs, the noise levels have been significantly decreased by clipping the rear, counter-rotating Propeller. Unfortunately, this comes at a cost of decreased efficiency. An alternative, potential solution lies with the Boxprop, which was invented by Richard Avellan and Anders Lundbladh. The Boxprop consist of blade pairs joined at the tip, and are conceptually similar to box wings. It is hypothesized that the Boxprop can eliminate the tip vortex found in Conventional blades, consequently increasing the efficiency of the blades, and reducing their acoustic signature. The present work highlights advances done in the research surrounding the Boxprop. A validation of the deployed CFD methodology is presented, in which numerical and experimental results compare favourably. Performance results for a Boxprop (GP-X-701) designed for cruise conditions are presented and compared with a generic Conventional Propeller (GP-S-609). It is shown that the present Boxprop cruise design can reach the required thrust for replacing the front rotor of a modern CROR, but with increased swirl relative to the analyzed Conventional Propeller. This is mainly due to the effect of the blade passage unloading one of the Boxprop blade halves near the tip, forcing the blade to be more highly loaded closer to the hub. The swirl generated by the Boxprop could be partially recovered if it is used together with a rear counter-rotating Propeller. A Wake Analysis Method (WAM) is presented in this work and is used to quantify the power flows inherent to the flow features of the Propeller wake. The power flows can be characterized as propulsively beneficial, recoverable, or pure losses. It has the ability to distinguish the kinetic energies of the tip vortices, wakes, and other disturbances from the flow field. The Wake Analysis Method was applied on the two Propellers mentioned earlier, and confirmed that the Boxprop produces 50\% more swirl than the Conventional Propeller. Additionally, the method very clearly shows the lack of tip vortex on the Boxprop, and the presence of it in the flow field of the Conventional Propeller.
Veldhuis L.l.m. - One of the best experts on this subject based on the ideXlab platform.
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Wingtip-Mounted Propellers: Aerodynamic Analysis of Interaction Effects and Comparison with Conventional Layout
'American Institute of Aeronautics and Astronautics (AIAA)', 2019Co-Authors: Sinnige T., Van Arnhem N., Stokkermans T.c.a., Eitelberg G., Veldhuis L.l.m.Abstract:Wingtip-mounted Propellers installed in a tractor configuration can decrease the wing induced drag by attenuating the wingtip vortex by the Propeller slipstream. This paper presents an aerodynamic analysis of the Propeller-wing interaction effects for the wingtip-mounted Propeller configuration, including a comparison with a Conventional configuration with the Propeller mounted on the inboard part of the wing. Measurements were taken in a low-speed wind tunnel at Delft University of Technology, with two wing models and a low-speed Propeller. Particle-image-velocimetry measurements downstream of a symmetric wing with integrated flap highlighted the swirl reductions characteristic of the wingtip-mounted Propeller due to wingtip-vortex attenuation and swirl recovery. External-balance and surface-pressure measurements confirmed that this led to an induced-drag reduction with inboard-up Propeller rotation. In a direct comparison with a Conventional Propeller-wing layout, the wingtip-mounted configuration showed a drag reduction of around 15% at a lift coefficient of 0.5 and a thrust coefficient of 0.12. This aerodynamic benefit increased upon increasing the wing lift coefficient and Propeller thrust setting. An analysis of the wing performance showed that the aerodynamic benefit of the wingtip-mounted Propeller was due to an increase of the wing's effective span-efficiency parameter.Flight Performance and Propulsio
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Wingtip-Mounted Propellers: Aerodynamic Analysis of Interaction Effects and Comparison with Conventional Layout
2019Co-Authors: Sinnige T., Van Arnhem N., Stokkermans T.c.a., Eitelberg G., Veldhuis L.l.m.Abstract:Wingtip-mounted Propellers installed in a tractor configuration can decrease the wing induced drag by attenuating the wingtip vortex by the Propeller slipstream. This paper presents an aerodynamic analysis of the Propeller-wing interaction effects for the wingtip-mounted Propeller configuration, including a comparison with a Conventional configuration with the Propeller mounted on the inboard part of the wing. Measurements were taken in a low-speed wind tunnel at Delft University of Technology, with two wing models and a low-speed Propeller. Particle-image-velocimetry measurements downstream of a symmetric wing with integrated flap highlighted the swirl reductions characteristic of the wingtip-mounted Propeller due to wingtip-vortex attenuation and swirl recovery. External-balance and surface-pressure measurements confirmed that this led to an induced-drag reduction with inboard-up Propeller rotation. In a direct comparison with a Conventional Propeller-wing layout, the wingtip-mounted configuration showed a drag reduction of around 15% at a lift coefficient of 0.5 and a thrust coefficient of 0.12. This aerodynamic benefit increased upon increasing the wing lift coefficient and Propeller thrust setting. An analysis of the wing performance showed that the aerodynamic benefit of the wingtip-mounted Propeller was due to an increase of the wing's effective span-efficiency parameter.
Anders Lundbladh - One of the best experts on this subject based on the ideXlab platform.
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Aeroacoustic analysis of aerodynamically optimized joined-blade Propeller for future electric aircraft at cruise and take-off
Aerospace Science and Technology, 2020Co-Authors: Zhongjie Huang, Anders Lundbladh, Huadong Yao, Oliver Sjögren, Lars DavidsonAbstract:A novel Propeller with the blade tips joined in pairs, named Boxprop, is designed and optimized for a conceptual electric aircraft using an efficient optimization platform. According to the thrust requirement of the electric aircraft at cruise, the Boxprop with optimal efficiency is down-selected from the Pareto front of thrust coefficient and Propeller efficiency. Furthermore, the blade pitch angle is adjusted to meet the thrust requirement at take-off. It is found that the Boxprop is capable of suppressing tip vortices and inducing a wider wake behind blade tip in comparison to a Conventional Propeller usually shedding a concentrated tip vortex, which could potentially improve the propulsive efficiency. Afterwards, the aeroacoustic analysis performed by the hybrid integral method of Reynolds-Averaged Navier Stokes equations (RANS) and convected Ffowcs Williams and Hawkings (FW-H) equation shows that the tonal noise from the Boxprop with three joined blades operating at cruise is similar to a Conventional three-bladed Propeller, though being stronger than a Conventional six-bladed Propeller. Although the tip vortices have been suppressed by the joined-blade tips of the Boxprop, the corresponding tonal noise reduction is not prominent. Next, the Boxprop noise at take-off is studied. Unsteady RANS is used to resolve varying flow structures that become dominant under the take-off condition. Angle of attack (AOA) is found as an important factor influencing the noise generation. The radiated noise upstream and downstream of the Propeller significantly intensifies due to increasing AOA. The AOA effects of the Boxprop follow a similar trend to a Conventional Propeller. The findings for the Boxprop aeroacoustics have enhanced the understanding of tip-vortex suppression techniques in connection with the tonal noise generation, which will be greatly helpful to the aeroacoustic design of Boxprop applied to electric aircraft in the future.
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Wake Analysis of an Aerodynamically Optimized Boxprop High Speed Propeller
Journal of Turbomachinery, 2019Co-Authors: Alexandre Capitao Patrao, Anders Lundbladh, Tomas Grönstedt, Gonzalo Montero VillarAbstract:The Boxprop is a novel, double-bladed, tip-joined Propeller for high-speed flight. The concept draws inspiration from the box wing concept and could potentially decrease tip vortex strength compared with Conventional Propeller blades. Early Boxprop designs experienced significant amounts of blade interference. By performing a wake analysis and quantifying the various losses of the flow, it could be seen that these Boxprop designs produced 45% more swirl than a Conventional reference blade. The reason for this was the proximity of the Boxprop blade halves to each other, which prevented the Boxprop from achieving the required aerodynamic loading on the outer parts of the blade. This paper presents an aerodynamic optimization of a 6-bladed Boxprop aiming at maximizing efficiency and thrust at cruise. A geometric parametrization has been adopted which decreases interference by allowing the blade halves to be swept in opposite directions. Compared with an earlier equal-thrust Boxprop design, the optimized design features a 7% percentage point increase in Propeller efficiency and a lower amount of swirl and entropy generation. A vortex-like structure has also appeared downstream of the optimized Boxprop, but with two key differences relative to Conventional Propellers. (1) Its formation differs from a traditional tip vortex and (2) it is 46% weaker than the tip vortex of an optimized 12-bladed Conventional Propeller.
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Aerodynamic and aeroacoustic comparison of optimized high-speed Propeller blades
2018 Joint Propulsion Conference, 2018Co-Authors: Alexandre Capitao Patrao, Daniel Lindblad, Anders Lundbladh, Tomas GrönstedtAbstract:The Boxprop is a high-speed Propeller concept intended for aircraft engines, which features blade pairs connected at the tip in order to decrease tip vortex strength, possibly reducing noise and improving aerodynamic performance relative to Conventional high-speed Propellers. This paper investigates the aerodynamic and aeroacoustic performance of three aerodynamically optimized high speed Propellers; a 6-bladed Conventional Propeller, a 12-bladed Conventional Propeller, and a 6-bladed Boxprop. Performance results will be be compared for the three designs, with a focus on sectional performance and wake flow characteristics, and will show that the 6-bladed Boxprop performance lies somewhat in-between its 6 and 12-bladed Conventional counterparts. The noise level at various observer positions is presented, and shows that the noise roughly follows the values of efficiency for the three Propellers, with the Boxprop noise level being higher than the 12-bladed Conventional Propeller, but lower than the 6-bladed one. The lower blade loading and higher efficiency of the Boxprop relative to the 6-bladed Conventional Propeller results in slightly lower levels of noise at cruise.
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wake and loss analysis for a double bladed swept Propeller
Proceedings of ASME Turbo Expo 2016: Turbine Technical Conference and Exposition Seoul South Korea Jun 13-17 2016, 2016Co-Authors: Alexandre Capitao Patrao, Anders Lundbladh, Richard Avellan, Tomas GrönstedtAbstract:Inspired by Prandtl’s theory on aircraft wings with minimum induced drag, the authors introduced a double-bladed Propeller, the Boxprop, intended for high-speed flight. The basic idea is to join the Propeller blades pair-wise at the tip to improve aerodynamics and mechanical properties compared to the Conventional Propeller. The rather complex geometry of the double blades gives rise to new questions, particularly regarding the aerodynamics. This paper presents a Propeller wake energy analysis method which gives a better understanding of the potential performance benefits of the Boxprop and a means to improve its design. CFD analysis of a five bladed Boxprop demonstrated its ability to generate typical levels of cruise thrust at a flight speed of Mach 0.75. The present work shows that the near tip velocity variations in the wake are weaker for this Propeller than a Conventional one, which is an indication that a counter rotating Propeller designed with a Boxprop employed at the front may exhibit lower interaction noise.
Tomas Grönstedt - One of the best experts on this subject based on the ideXlab platform.
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Wake Analysis of an Aerodynamically Optimized Boxprop High Speed Propeller
Journal of Turbomachinery, 2019Co-Authors: Alexandre Capitao Patrao, Anders Lundbladh, Tomas Grönstedt, Gonzalo Montero VillarAbstract:The Boxprop is a novel, double-bladed, tip-joined Propeller for high-speed flight. The concept draws inspiration from the box wing concept and could potentially decrease tip vortex strength compared with Conventional Propeller blades. Early Boxprop designs experienced significant amounts of blade interference. By performing a wake analysis and quantifying the various losses of the flow, it could be seen that these Boxprop designs produced 45% more swirl than a Conventional reference blade. The reason for this was the proximity of the Boxprop blade halves to each other, which prevented the Boxprop from achieving the required aerodynamic loading on the outer parts of the blade. This paper presents an aerodynamic optimization of a 6-bladed Boxprop aiming at maximizing efficiency and thrust at cruise. A geometric parametrization has been adopted which decreases interference by allowing the blade halves to be swept in opposite directions. Compared with an earlier equal-thrust Boxprop design, the optimized design features a 7% percentage point increase in Propeller efficiency and a lower amount of swirl and entropy generation. A vortex-like structure has also appeared downstream of the optimized Boxprop, but with two key differences relative to Conventional Propellers. (1) Its formation differs from a traditional tip vortex and (2) it is 46% weaker than the tip vortex of an optimized 12-bladed Conventional Propeller.
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Aerodynamic and aeroacoustic comparison of optimized high-speed Propeller blades
2018 Joint Propulsion Conference, 2018Co-Authors: Alexandre Capitao Patrao, Daniel Lindblad, Anders Lundbladh, Tomas GrönstedtAbstract:The Boxprop is a high-speed Propeller concept intended for aircraft engines, which features blade pairs connected at the tip in order to decrease tip vortex strength, possibly reducing noise and improving aerodynamic performance relative to Conventional high-speed Propellers. This paper investigates the aerodynamic and aeroacoustic performance of three aerodynamically optimized high speed Propellers; a 6-bladed Conventional Propeller, a 12-bladed Conventional Propeller, and a 6-bladed Boxprop. Performance results will be be compared for the three designs, with a focus on sectional performance and wake flow characteristics, and will show that the 6-bladed Boxprop performance lies somewhat in-between its 6 and 12-bladed Conventional counterparts. The noise level at various observer positions is presented, and shows that the noise roughly follows the values of efficiency for the three Propellers, with the Boxprop noise level being higher than the 12-bladed Conventional Propeller, but lower than the 6-bladed one. The lower blade loading and higher efficiency of the Boxprop relative to the 6-bladed Conventional Propeller results in slightly lower levels of noise at cruise.
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wake and loss analysis for a double bladed swept Propeller
Proceedings of ASME Turbo Expo 2016: Turbine Technical Conference and Exposition Seoul South Korea Jun 13-17 2016, 2016Co-Authors: Alexandre Capitao Patrao, Anders Lundbladh, Richard Avellan, Tomas GrönstedtAbstract:Inspired by Prandtl’s theory on aircraft wings with minimum induced drag, the authors introduced a double-bladed Propeller, the Boxprop, intended for high-speed flight. The basic idea is to join the Propeller blades pair-wise at the tip to improve aerodynamics and mechanical properties compared to the Conventional Propeller. The rather complex geometry of the double blades gives rise to new questions, particularly regarding the aerodynamics. This paper presents a Propeller wake energy analysis method which gives a better understanding of the potential performance benefits of the Boxprop and a means to improve its design. CFD analysis of a five bladed Boxprop demonstrated its ability to generate typical levels of cruise thrust at a flight speed of Mach 0.75. The present work shows that the near tip velocity variations in the wake are weaker for this Propeller than a Conventional one, which is an indication that a counter rotating Propeller designed with a Boxprop employed at the front may exhibit lower interaction noise.